三峡山地不同垂直带土壤层的水文功能及其影响因子

Soil Hydrological Function of Different Altitudinal Hillslopes of the Three Gorges Mountain and Its Impact Factors

渗透性能和持水能力是土壤重要的水力学性质,是土壤调节径流、保持水土和涵养水源等水文功能的基础。以三峡库首的夷陵-大老岭山地为对象,采集亚高山棕壤针叶林地、中山黄棕壤针阔混交林与茶园地和低山黄壤针叶林地等4个样点剖面的土壤样品,在室内进行土壤饱和导水率、水分特征曲线和理化性质测定,量化了不同样地土壤渗透性能、持水能力和水分库容等水文功能参数,并明确了其主要影响因子。结果表明:研究区山地土壤饱和导水率在0.06~14.78 mm/min之间,亚高山棕壤和中山黄棕壤林地土壤渗透性能较好,其平均饱和导水率在7.15~14.78 mm/min之间,低山黄壤次之(1.3 9 mm/min),中山黄棕壤茶园土壤渗透能力最差(1.17 mm/min)。不同类型土壤的饱和含水量、毛管含水量、田间持水量存在较大差异,凋萎含水量差异较小。同一类型土壤的不同发生层内,土壤饱和含水量随土壤深度的增加而递减,毛管持水量和田间持水量随土层深度的增加波动上升。不同样地间土壤水分总库容差异较大,随着海拔的升高,土壤水分总库容增加。土壤水分特征参数与土壤性质的相关分析表明,饱和导水率与土壤总孔隙度呈显著正相关,与容重呈显著负相关;饱和含水量、毛管持水量、田间持水量均与土壤总孔隙度、粘粒含量呈显著性正相关,与容重呈显著负相关;饱和含水量与根系重量呈显著正相关;毛管持水量、田间持水量与砂粒含量呈显著负相关。与中山茶园地和低山黄壤林地相比,亚高山棕壤和中山黄棕壤林地渗透性能较好且持水性更强,具有更好的调蓄径流和涵养水源的水文功能。

Soil permeability and water holding capacity are important soil hydraulic properties,which are also the basis of some hydrological functions,such as runoff regulation,and soil and water conservation. Four sampling locations in the head region of the Three Gorges Reservoir Area were selected to collect the soil samples,which contained the brown soil covered with subalpine temperate coniferous forest（ BF）,the yellow brown soil covered with deciduous coniferous broad-leaved mixed shrubs（ YBF）,the yellow brown soil covered with tea tree（ YBT）,and the yellow soil covered with low-mountain warm coniferous forest（ YF）. Soil saturated hydraulic conductivities（ Ks）,soil water retention curves and physiochemical properties of these soil samples were analyzed in the lab, and the soil hydrological parameters of soil infiltration, water holding and water storage were quantified. Furthermore,the relationships between the hydrological parameters and soil physiochemical properties were analyzed. The results indicated that Ks ranged from 0. 06 to 14. 78 mm/min for all the soil samples. The highest Ks was observed from BF and YBF（ i. e.,7. 15 ~ 14. 78 mm/min）,followed by YF（ 1. 39 mm/min）,and YBT（ 1. 17 mm/min）. Significant differences of the saturated soil water content,capillary water content and field water capacity were observed among the four sampling locations,but little difference of wilting water content was identified. The soil properties of different horizons for the same soil profile was evaluated. With increasing soil depth,the saturated water content decreased,whereas the capillary water content and field capacity increased.Significant differences of the total water capacity were identified among the four sampling locations,and the total water capacity increased as the altitude increased. Correlation analysis between soil water parameters and soil properties indicated a significantly positive correlation between Ks and soil total porosity,and a significantly negative correlation between Ks and soil bulk density. There were significantly positive correlations between the saturated water content/capillary water content/field water capacity and total porosity/clay content, but significantly negative correlations with the soil bulk density. In addition,a significantly positive correlation was observed between the saturated water content and root density,whereas significantly negative correlations between capillary water content/field water capacity and the sand content were identified. Compared to YBT and YF,BF and YBF were characterized by higher infiltration rate and water holding capacity,behaving the better soil hydrological functions of runoff regulation and water conservation.